Telephone system



Oct. 15, 1929. M, slMPsON l 1,731,943

Filed Nov. 30, 1927 Humm Lancsla Ns Sim 5cm Patented ou. 15, 19219 UITED STATES PT NT OFFICE LANGELOT MARTIN SIMPSON, OF THORNER, NEAR LEEDS, ENGLAND, ASSIGNOR T0 ASSOCATED TELEPHONE AND TELEGRAPI- COMPANY, F KANSAS CITY, MISSOURI,

.A CORPORATIQN OF DELAWARE TELEPHNE SYSTEM Application led November SO, 1927, Serial No. 236,715, and in Great Britain April 2S, 1927.

The present invention relates to telephone systems; more particularly to systems employing automatic numerical switches in serial relationship and is especially applicable to the routine testing of repeaters, relay groups, and so-called first code selec tors, though certain o'l its features are capable of wider application. In many cases the numbering scheme will not permit the allocation of a selectorlevel for routine testing purposes and the object of the present invention is to enable the testing to be carried out over a selector level withouta corresponding sacriice ot numbers, a particular subscribers number being used as the test number.

lith final selectors arranged for battery :teeding, the normal negative and positive line conductors cannot be used for testing purposes owing to the condensers and battery feed relays associated therewith in the tinaly selector. In order to ascertain whether repeaters, relay groups and first code selectors ol the type considered are functioning correctly, it is necessary to operate them through various resistances and for this purpose a clear metallic circuit for the operating impulses is necessary. The routiner circuit is arranged to supply ringing current and the impulses necessary to operate switches of the type considered, but it should be understood that the present invention is not limited to the use of any particular routiner circuits although in order that the invention may be more clearlyunderstood reference may be made to application of John Ellis Ostline, Serial No. 222,456, tiled September 28, 1927, in which a detailed description ot the operation of an appropriate routiner is given.

According to one feature ot the present invention the required objects areattained by the use of an automatic switch adapted to hunt to find a markedcontact in which the special marking consists in the application of alternating current to the required contact.

In order that the invention may be more fully understood and readily carried into effeet, a system making use ot the principles of the invention will now be described with reference to the accompanying single sheet of drawings. It will be understood, however, that this arrangement is given by way oi example only and that various alterations may be made in the circuit details without exceeding the scope of the invention.

Figure l shows the trunking arrangement for rout-ine testing iirst codeA selectors in a tull automatic exchange, and Figure 2 shows the circuit arrangementof the auxiliary equipment locatedbetween the routine testing` equipment and the connector.

Referring to Figure l, an ordinary local call trom the substation SA to substation SB is set up over the rotary line switch RLS, trunk relay group TEG, lirst code selector FCS, iirst numerical selector S, and connector FS to the subscriber SB.

in exchange attendant Wishing to routine test a group ot :first code selectors will operate a start key associated with the routine eating equipment RTE, whereupon the dis-` tributor switch DS will advance into "engagement with the lirst switch in the group. lf this trunk is free the routine testing equipment automatically sends out the test number. Should the lirst trunk be busy, the impulse sending apparatus in the routine testing equipment delays sending for apredeterniined interval and then steps on to the nent trunk. Assuming that the trunk relay group shown in the drawing is idle, the routine equipment RTE will send out the necessary impulses to extend the connection to the number allocated tor testing purposes in the bank ot the connector.

The extension of the connection to this number causes the trunk linder TF to lind the trunk incoming to the connector and to switch the connection from the selector S into the routiner and disconnect the trunk to the connector.

Referring now to Figure 2, the equipment illustrated comprises a trunk finder TF, switching relay SR and auxiliary relays ARI, ARQ, tilts, Altt. The switching relay SR is individual to each connector of the group in which its test number appears. The auxiliary relays AE1, ABZ, ARS, ARt and the trunk finder TF are common to the group of connectors. When the connector FS isset on the test number, ground is eX- tended over the `private wiper P2 to relay AR3 which takes the place of the regular 5 subscribers cut 0E relay. Relay ARs upon operating,A connectsv the number unobtainable tone conductor NUT to the negative bank contact .B2` and speaking conductor Aat armaturef?. and lat armature connects the 1 ground time pulses conductor PC to the two step pulseV absorbing relay AR. Pulses at the rate of 10 pulses per second are connected tothe conductor PC. p The first pulse on conductor 'PC will cause two-step relay AR*l to close its X contacts and when this pulse is removed relay AR4 willenerg'ize over both its windings in series'in the following circuit: battery, lower andupper windings in series, X contacts,

- 2Q armature 25 of relay AR2 and its back contact to the grounded holding conductor HC. Relay' AR.4 now. operates and at armature 13 extends'the pulse conductorPC to the driving magnet DM of the trunk finder TF; 2i; During this period the routiner RTE is arranged to connect ringing current to the positiveline 'conductor A; The trunk finder is operated by pulses from conductor PC and; advances its' Wipers 14,' 15, and 16 untiliwpi 141 findsthe contact to which ringing' current V,is connected. vVhen wiper 14 engages a contact to whichY ringing current has been applied a circuit is completed i for lthe alternating current relay AR1 which y 435 energizes inthe following circuit: ground,

relay ARi, condenser C, wiper 14, armature 17 1offrelayfvSR.and its back contact, con- -ductcr'A,to ringing current connected up in'the'routiner. Relay AR1 upon operating, 40 connects at .armature 22, the holding conductor HC, which is grounded in the routiner, to the switching relay SR over wiper 15. Rela SR upon operating, completes a v locking circuit 'for-itself to the 'holding con- 4`5 ductor HG at armature 2,0, and at armatures 17 .and 18 disconnects the positive and negative speaking conductors A1, B1 from the positive `and negative speaking conductors AgfB'leadin'g to the connector kFS and se'extends them to the impulse acceptin relay in .the yroutiner over thecommon con uctors A213s and yatarmature 19 disconnects the rivate conductor P1 of the incoming seectoir ltrunkfrom the private conductor of connector trunk and grounds the former, therebyV rendering it busy -to other switches and to hold up the preceding switches. The connector now releases and removes ground from private wiper P2, ythis `6o however,is without eieGb vas the trunk finder 'TF' has ,ceased hunting. Relay SR, at armature '21, also completes a circuit for relay ARz. Relay AR2 upon operating, opens the locking circuit for two step pulse absorbing i relay AR* at armature 25 and at armature 26 completes a homing circuit for the driving magnet DM. The number unobtainable tone is connected to the negative line of the test number in case a subscriber should dial the testnumber by mistake, when he will receive the usual dead number 'tone signal.

At the end of routine testing operation ground potential is removed from the holding conductor HC whereupon switching relay SR releases and opens its own locking circuit at armature 2O and connects the incoming trunk to the connector FS again at armatures 17, 18 and 19. It sometimes happens ithat an exchange attendant will advance the wipers of the trunk finder TF by hand and in order to ensure that this switch will be returned to its normal position the following circuit is arranged over its wiper 16 and interrupter contacts 27; ground resting contact and armature 11, resting contact and armature 26, Wiper 16 and its associated common bank contacts, interrupter contacts 27, winding of magnet DM to battery.

"What is .claimed is:

1. In a telephone system, a switch having a contact bank, means for marking any contact in that bank with alternating current, and means 'for .operating said switch to hunt for said marked Contact.

2. In a telephone system, selector switches, connector switches, means for establishing a connection over a path including one of Yeach of said switches, and means responsive to the establishment of a connection for releasing -the connector switch and connecting the -selector switch to the first mentioned means.

3. In a telephone system, a group of primary switches, a group of secondary switches, means for establishing a connection over one of each of said switches, and an auxiliary switch responsive .to the establishingof a connection for hunting for the secondary switch in the connection and for thereafter releasing the secondary switch and connecting the primary switch to said means.

4. In atelephone system, selector switches, connector switches, a plurality of means for establishing connections over paths including one of each of said switches, and means responsive to the establishment of connections by certain of said Vfirst means for releasing connectors in said connections and connecting the selectors to said certain means.

5. In a telephone system, selector switches, connector switches, means for establishing a connection over one of each of said switches, testing equipment having means for establishing a connection over one of each of said switches, and means responsive to the establishment of a connection by said equipment tor releasing the connector and connecting the selector to said equipment.

6. In a telephone system, selector switches, connector switches, means for establishing a connection over one of each of said switches,

testing equipment having means lor establishing a connection over one of each of said switches, also, and an auxiliary switch opern ated responsive to the establishment of a connection by said equipment for disconnecting the selector switch from the connector switch and connecting the selector switch to said equipment.

7. In a telephone system, selectors, con nectors, trunks, means for establishing a connection over a path including one of said selectors, one of said trunks and one of said connectors, and an auxiliary switch operated responsive to the establishment of a conncction for hunting for the connecting trunk and ior thereafter switching said trunk from said connector to said means.

S. In a telephone system, selector switches, trunks, connector switches accessible to said selectors over said trunks, means for establishing a connection over a path including one of said selectors, one of said trunks and one of said connectors, testing equipment having means for establishing a connection over a similar path, and an auxiliary switch operated responsive to the establishment of a connection by said equipment for hunting for the trunk in that connection and for thereafter disconnecting said trunk from the connector switch and connecting it to said equipment.

9. In a telephone system, selector switches, trunks, connector switches accessible to said selectors over said trunks, means for establishing a connection over a path including one of said selectors, one of said trunks and one of said connectors, testing equipment having means for establishing a connection over a similar path, means in said equipment for projecting alternating current over the trunk in the connection established thereby, and an auxiliary switch operated responsive to the establishment of a connection by said equipment for hunting for the trunk marked by alternating current and for thereafter causing said trunk to be disconnected from the connector and connected to said equipment.

l0. In a telephone system, selector switches, trunks, connector switches accessible to said selector switches over said trunks, testing equipment having means for establishing a connection over a path including one of said selectors, one of said trunks and one of said connectors, means in said equipment for projecting alternating current over said trunk, and an auxiliary switch operated responsive to the establishment of said connection for hunting for said trunk, an alternating current relay in said auxiliary switch operated responsive to the iinding of said trunk, and means associated with said trunk and operated responsive to the operation of said relay for disconnecting said trunk from the connector switch and connecting the trunk to said equipment.

l1. In a telephone system, aswitch having 

